1. Field of the Invention
The invention relates to a device to adjust the orientation of a mirror of a motorcar according to the Device to adjust the orientation of a mirror of a motorcar, comprising a body accommodating a first and a second electric motor and a first and a second gear driven by said first and second motor respectively, a reflective element support pivot-mounted at the body in relation to two pivot axles, at which reflective element support two gear rods are arranged engaging with said gears, a first gear rod engaging with the first gear to pivot the reflective element support around a first pivot axle and a second gear rod engaging with the second gear to pivot the reflective element support around a second pivot axle, wherein gear rods are formed as circular arc sections each and the body accommodates means to springy press the first and second gear rod against the first and second gear respectively, eliminating relative movement between the gearing of the gear rods and the gears in operation conditions, and the gears comprise safety clutch means each, allowing the gears to slip in overload conditions, characterized in that the safety clutch means comprise a disc spring having a friction face forced against a corresponding friction face on another gear train member.
2. Description of the Related Art
To adjust the orientation particularly of a door mirror of a motorcar, devices are known comprising electric motors whose shafts via motion transmission means are connected with a reflective element support, on which a reflective element, such as a mirror, is arranged.
In order to provide low cost light weight devices, most components, like e.g. body, reflective element support, transmission means such as gears and gear rods and the like, the bearing between the body and the reflective element support, are constructed from polymers including various plastics. With plastics, at least in comparison with metals, it is difficult to achieve required manufacturing tolerances, resulting in slackness and thus little movement or judder of the reflective element support around zero position. This leads to delayed response characteristics when adjusting the orientation of the mirror, since the electric motors in the very beginning of each adjustment procedure first have to break the slackness of the device, particularly of the transmission means. The slackness can also result in judder of the door mirrors at high speeds of a motorcar.
To counteract the judder, it is known to damp the movement of the reflective element support against the body by friction, disadvantageously resulting in abrasion and thus degeneration with increasing operating time.
From EP 0 596 182 A1 a device to adjust the orientation of a mirror of a motorcar is known, which comprises a body accommodating a first and a second electric motor and a first and a second worm drive driven by said first and second motor respectively. The device further comprises a reflective element support pivot-mounted at the body in relation to two perpendicular pivot axles, at which support two gear rods are arranged, each one engaging with said worm drives, a first gear rod engaging with the first worm drive to pivot the reflective element support around a first pivot axle and a second gear rod engaging with the second worm drive to pivot the reflective element support around a second pivot axle. Each gear rod is clipped on the reflective element support by inserting it into a mounting seat and engaging an end hole on a pivot. The latter is radially orientated towards the centre of the reflective element support and comprises a spherical projection on one of its ends retaining the gear rod on the pivot. This arrangement results in that the gear rod can commute in all directions relative to the reflective element support. To maintain the coupling between the commuting gear rods and the worm screws, springs are foreseen within the body. Disadvantageously this arrangement does not reduce slackness and thus judder because of the slackness of the commuting gear rods. A further disadvantage of this device is, that when manually adjusting the mirror, or, during overload conditions e.g. due to internal or external forces, the worm drives avoid back driving the gear and thus the electric motors. Due to this in overload conditions the springs have to allow the gear rods to disengage the worm drives and to skip their gearings. This results in noises and also abrasions of the gearing of the gear rods and worm drives.
From U.S. Pat. No. 5,701,211 a device to adjust the orientation of a mirror of a motorcar is known, which comprises a body accommodating a first and a second electric motor and a first and a second gear train driven by said first and second motor respectively. The device further comprises a reflective element support pivot-mounted at the body in relation to two perpendicular pivot axles, at which support two gear rods are arranged, each one engaging with said gear trains, a first gear rod engaging with the first gear train to pivot the reflective element support around a first pivot axle and a second gear rod engaging with the second gear train to pivot the reflective element support around a second pivot axle. Each gear rod is mounted at the reflective element support by a ball head, allowing it to commute in any direction. In order to guide the gear rods in a duct through which they enter the body, a spring is arranged within said duct.
A disadvantage of all known devices is, that for a given angle of travel they require a relatively large, particularly deep installation space.